packet size

[Matthew Horsfall (alh)]

On Wed, Sep 11, 2013 at 12:24 PM, Maria Iano <bind-lists at iano.org> wrote:
>
> What does it mean when the edns0 response to a dig says the overall packet size will be one value but the message size reported is different. For example in this reponse the OPT PSEUDOSECTION says udp: 4096 but at the end it says MSG SIZE  rcvd: 275.

The "udp: 4096" in the OPT PSEUDOSECTION is the nameserver that you
queried reporting it's max udp packet size that it can accept:

>From http://tools.ietf.org/html/rfc2671:

4.5. The sender's UDP payload size (which OPT stores in the RR CLASS
     field) is the number of octets of the largest UDP payload that can
     be reassembled and delivered in the sender's network stack.  Note
     that path MTU, with or without fragmentation, may be smaller than
     this.

-- Matthew Horsfall (alh)